Lens QWERTYUIOP

Ok so the deal is right now I’m looking at either a Sigma 70-200 f/2.8 or a nikkor 80-200 2.8. But I see there is the AF-D and the AF-S version of the Nikkor. I can’t find the AF-S anywhere on B&H or anything.. is this an older model? What are the pros and cons of af-s and af-d? Isn’t af-s for single shots and af-d for continuous shooting?

Please help as I’m pretty much a noob at all of this newfangled fancy lens stuff.. what with all the “dg” and “apo” and “hsm” and “d” and “qwertyuiop” lenses

The problem is the AF-S is now sold under 70-200mm, not 80-200mm which is discontinued. AF-S’s are a newer model.

Your first confusion is that Nikon has overloaded the “AF-S” term. On D70-level camera’s “AF-S” stands in contrast to AF-C and stands for single and continuous focusing (which is actually overloaded with two distinct focusing features that are separate on a Nikon D200-level camera).

On lenses, AF-D is actually now just “D” and stands for the addition of distance information delivered through to the metering system. This assists greatly in flash metering. In many new lenses this has been repalced with “G” where the aperture ring has been removed for a cost savings (and thus requiring camera bodies that can control the aperture electronically).

“AF-S” stands for an internal piezoelectric motor included with the lens, (Nikon calls this a Supersonic Wave Motor or SWM).

In the older 80-200mm models, there are three that are tagged in the group: 80-200mm f/2.8D (the AF-D you allude to), the 80-200mm f/2.8D new (an improved design introduced in 1998 that allowed for faster internal focusing and added a tripod collar), 80-200mm f/2.8D AF-S (the AF-S you allude to). For the sake of completness there was also an 80-200 f/2.8 AF and 80-200 f/2.8 AI-s, but nobody shoots with those anymore.

[A breakdown of lens acronyms after the jump]

Lenses drive usage

The story of lens technology is the story of the SLR camera. Though many Canon owners never buy an L lens in their life, the L mystique drives them to continually purchase cameras. The reputation of Nikkor lenses is still unmatched by Canon because of all the investment put into optics.

Today Canon is the dominant manufacturer in the dSLR world pretty much because of the introduction of the USM motor in their EOS lens design and cemented by the introduction of Image Stabilization. Nikon’s ascendency and dominance is because of F-mount and the interchangeable everything system it spawned. Explain if their would be a “Leica look” and books in every serious photography store devoted the the M-system if they had not invented the first interchangeable 35mm rangefinders?

Lens acronym fun

I’ve done this in the past here and there, but I want to start building a more definitive list. This will have to be a work in progress. I am only covering lens technologies here, not lens compatibility. If you own a Canon, it’s trivial, but if you own a Nikon like me, you know why that’s a book unto itself, or check here.

Actually these are not the same at all. What these means in the case of the major manufactueres is that these are the mount designs for the premier lens systems of each company.

The bayonet mountis arguably the greatest single invention to hit SLR photography, for SLR is synonymous with interchangeable lenses (even though the acronym has nothing to do with it) and the bayonet makes this a practical reality. Over time, these mount designs had to be updated or changed to share electronic lens data and auto focusing support with the camera body.

Before 1959, Nikon was just an optics company (Nikkor). After that, the F mount was created and a legend was born. While the most venerable mount, it isn’t the most compatible—some F mount lenses would actually crash the mirror of today’s cameras. That title belongs to the Pentax K mount in which you can use any lens manufactured by Pentax after it’s introduction in 1976 with any Pentax body.

Instead of gradually shifting their customers to a new lens design like Nikon or ensuring full backward compatibility like Pentax, Canon had a tendency to screw over their customers with a completely new lens system that followed each new technology. Finally in 1987, they settled on the EOS System all of which have the lens designation “EF.” One huge advantage of this approach was a completely electronically and independently controlled aperture and auto-focusing system. This makes the AF and aperture controls slightly more reliable than the Nikon F mount. (The Sigma S mount and the Four-Thirds system also operate this way.) Another side advantage is a larger bore which allows it to be adapted to use Nikon F mount lenses in manual mode.

The Olympus four-thirds system is a complete and open redesign specifically for digital cameras. Because of the large bore, you can still mount and use Olympus OM lenses (as well as Nikon F, etc.), but it’s completely independent.

If you see a “Sigma DG” for Nikon cameras then for all intents and purposes it’s a “Nikon F” mount lens. This is to distinguish this from “Sigma S” which mounts on their own cameras.

Doing this increases transmittance which allows the multi-element zoom lenses you see today. In the old days, you’d have consider the T-stop in addition to the F-stop because of all the light lost reflecting off the glass. This also reduces lens flare and ghosting for the same reasons.

These are all proprietary multi-coats. I’m mentioning this because Pentax SMC is proprietary and Tokina has to use their own coatings for the Nikon and Canon markets even though they are otherwise the same as the Pentax designs.

This means the lens contains at least one glass element with a low index of refraction.

This allows lens designers to eliminate lateral chromatic abberations (purple fringing) at three color frequencies—at two this is called an achromat, at three, it is called apochromat.

Nikon introduced this idea in photographic cameras, but it originally came from the astronomy world where they use Fluorite, which is a type of low-dispersive transparent crystal. Since Fluorite is noth expensive and fragile, Canon switched from using it to mimicking Nikon’s ED glass. Canon thus claims that they introduced fluorite glass for photography, which is true but deceptive. Nikon used to distinguish their lenses which used ED glass with a gold ring. Since now a lot of cheaper lenses have ED glass, this is no longer the case and the gold ring has shifted to mimicking Canon’s L.

Normal cameras are turned with a screw motor in the camera body. Hysteresis compromises the accuracy. A screw motor won’t release after lock has been achieved. The mechanical action of a the screw turning makes a buzzing noise that you can hear.

With a “wave motor” the motor is is in the lens—As I mentioned above, this technology was the cause of the EOS system so all Canon EOS cameras don’t need a motor; the Nikon D40, for instance, has no motor in the body and thus can’t autofocus at all unless there is a SWM in the lens—this keeps in line with Nikon’s “gradually phasing out” old technology in the F-mount. There mechanic action is microscopic so the focusing accuracy is improved. It finishes in the unlocked position so you can easily adjust the focus after lock has been achieved. The noise it makes is completely silent to our ears.

I’m also told that in practice it focuses a fair bit faster than a normal screw motor. Theoretically this actually depends on the motor used in the body since we’re comparing apples to oranges.

Since this is a piece of engineering it should come as no surprise that Canon introduced this technology to photography and it comes by way of many optical and atomic physics lab benches. In 1996, Nikon got a hold of the rights to use this technology (it’s a Japanese thing) and now, since the patent has expired, a number of others manufacture lenses with these motors in them.

Nikon nanocrystal coat (N)

…more later…

Canon L = Sigma EX

A long time ago, it might have meant a fluorite element was used. This was probably in counterpoint the Nikon’s gold ring accent, but now it’s just a Canon market thing meaning “luxury.” Usually L lenses are costlier, heavier, better constructed, and have a larger aperture than their non-L counterparts. Due to advances such as USM and IS, the distinctive white body and red ring is now synonymous with “professional sport photography” in some circles. While there may be valid physics for the white body in astronomy, in photography the white lens is pure marketing, and brilliant I might add.